Cos(15°) = (√6 + √2)/4
Cosine — the x-coordinate of the corresponding unit-circle point, or adjacent/hypotenuse in a right triangle.
How to derive cos(15°)
Difference formula: cos(45° − 30°) = cos45°cos30° + sin45°sin30° = (√2/2)(√3/2) + (√2/2)(1/2) = (√6 + √2)/4.
Unit-circle context
The angle 15° corresponds to π/12 radians and sits Quadrant I on the unit circle.
Other trig values at 15°
Related cos values
Frequently asked
- What is the exact value of cos(15°)?
- The exact value is (√6 + √2)/4. Its decimal approximation is 0.96593.
- How do you derive cos(15°)?
- Difference formula: cos(45° − 30°) = cos45°cos30° + sin45°sin30° = (√2/2)(√3/2) + (√2/2)(1/2) = (√6 + √2)/4.
- What is 15° in radians?
- 15° equals π/12 radians (multiply degrees by π/180).
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